That reward will be administered by the Citizens Crime Commission and added to the $20,000 reward already offered by the city for tips leading to an arrest and conviction in the case.
Johnson, who represents the district where Ketunuti lived, called her killing a "cowardly act of wickedness" and implored citizens to pass along any tips that might help investigators crack the case.
"We want to make sure no rock is unturned when it comes to bringing someone to justice, but we need information," he said. "Here was a young lady who made a choice to move to the city of Philadelphia to pursue her career."
Ketunuti, 35, a second-year infectious-diseases fellow at CHOP, was found strangled, bound and set ablaze in the basement of her home on Naudain Street near 17th on Monday afternoon. So far, police said they've followed up on numerous tips and reviewed countless hours of surveillance video from the neighborhood.
"Ever since it happened on Monday, we've had detectives working around the clock," Homicide Unit Capt. James Clark said. "We're following a lot of leads, a lot of good tips, a lot of things we've seen in the video."
Clark said Tuesday that Ketunuti's boyfriend and the dog walker who found her body had been ruled out as suspects. But Wednesday, he said that no one who had contact with Ketunuti had been ruled out, adding that the investigation was "still very much open."
Investigators are still unsure whether Ketunuti was targeted or the killing was random. Clark said police still hadn't determined whether her killer had followed her.
Tipsters should contact police at 215-686-TIPS (8477) or the Citizens Crime Commission at 215-546-TIPS (8477).
On Twitter: @morganzalot